Is IES modelling hot water correctly?
Is IES modelling hot water correctly?
My latest attempt at using the IES SBEM has yet again gave me some problems. My hot water system is 90% efficient and according to the modelling guide the efficiency of the notional hot water system should be 83.6% so then why is the hot water energy in the notional way lower than the actual?
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Complex Potential
- VE Expert
- Posts: 467
- Joined: Wed Jan 09, 2013 11:57 am
- Location: Bristol, UK
Re: Is IES modelling hot water correctly?
Hi Ecoboost
I think the 83.6% is refering to the heat generation (boiler) efficiency. On top of that you also have the hot water delivery efficiency to consider which the notional building sets at an eye watering 95% (I think IES defaults to 80% for the actual building if you haven't changed it). Apologies if you have already considered this but it is not clear from your post.
CP
I think the 83.6% is refering to the heat generation (boiler) efficiency. On top of that you also have the hot water delivery efficiency to consider which the notional building sets at an eye watering 95% (I think IES defaults to 80% for the actual building if you haven't changed it). Apologies if you have already considered this but it is not clear from your post.
CP
Re: Is IES modelling hot water correctly?
Complex Potential is correct.
The DHW efficiency in the Notional Building should be between 92.63% and 94.74%, as follows:
Base = 83.6% (NCM guide table 6)
Delivery loss = 5% (NCM Guide paragraph 50. Our software sets delivery efficiency to 0.95 and increases the base efficiency) = 83.6 x (1/.95) = 88%
Power Factor: The notional building has the power factor of >0.95 i.e. the adjustment factors from ADL2A (2010) Table 2 apply. = 88 x (1/.95) = 92.63%
There are a number of roof lit activities in the database, which, in accordance with table 7 of the NCM Guide, has a base efficiency of 85.5%, hence the range between 92.63% and 94.74%.
I would also like to point out that VE-SBEM only writes out the inputs for the Actual building. The Notional building inputs are created by the SBEM engine itself based on the inputs it receives for the Actual building. IES has no control over this.
I hope this helps.
The DHW efficiency in the Notional Building should be between 92.63% and 94.74%, as follows:
Base = 83.6% (NCM guide table 6)
Delivery loss = 5% (NCM Guide paragraph 50. Our software sets delivery efficiency to 0.95 and increases the base efficiency) = 83.6 x (1/.95) = 88%
Power Factor: The notional building has the power factor of >0.95 i.e. the adjustment factors from ADL2A (2010) Table 2 apply. = 88 x (1/.95) = 92.63%
There are a number of roof lit activities in the database, which, in accordance with table 7 of the NCM Guide, has a base efficiency of 85.5%, hence the range between 92.63% and 94.74%.
I would also like to point out that VE-SBEM only writes out the inputs for the Actual building. The Notional building inputs are created by the SBEM engine itself based on the inputs it receives for the Actual building. IES has no control over this.
I hope this helps.